The present invention relates to a method, as well as to a system for transmitting data among various memory units of position measuring devices.
A memory unit is typically found inside the scanning unit of linear position measuring devices that are based on an optical scanning principle. Generally the memory unit is in the form of an EEPROM. It is customary for data specific to the particular position measuring device to be stored in the memory unit. These data are written into the memory unit either by the current user or by the manufacturer of the position measuring device. The data includes, for instance, data on the zero adjustment, clock pulse number, scale section, and other parameters. When a scanning unit of this kind breaks down, it is necessary to rewrite the specific data required for operation into the memory unit of the replacement scanning unit. This entails a large effort, particularly when working with a large quantity of stored data or measuring system-specific information. Moreover, difficulties can arise when reconstructing the original data.
Similar problems arise when the memory units in question are not disposed in the scanning unit, but elsewhere in the particular position measuring device. This is the case, for example, in rotary position measuring devices.
The present invention is a simplified and reliable method and system which permits the data in a memory unit being replaced to be passed on to a new memory unit, when replacement of a memory unit of the position measuring device is needed. The present invention provides for an automatic transfer, such as an automatic copying of the data from the first memory unit to be replaced, into the new, second memory unit. This can be more easily done when memory unit replacement is not necessitated by defects in the first memory unit. For example, a replacement can be necessary due to other problems with the scanning unit, when the memory unit is disposed in the scanning unit.
The user-specific data from the first memory unit to be replaced can be accepted rather simply into the new, second memory unit. Generally, such user-specific data cannot be reconstructed by the measuring system manufacturer as easily as the data that had been written into the memory unit by the measuring system manufacturer. It is important then that the replacement can be performed by the user rather than only by the manufacturer.
In addition, the method according to the present invention, permits the user to recognize whether the data transfer has been carried out correctly, or, in some instances, if transfer problems have occurred. It is even possible in one especially advantageous specific embodiment to identify the cause of the errors in the case of an incorrect data transfer. There are several ways in which errors can be recognized or faults can be identified. According to the invention, even in the case of a possibly defective signal processing unit or processor, the data from a scanning unit to be replaced can be automatically transferred into the new memory unit.
Moreover, the embodiments in accordance with the present invention ensure that the electrical consumption of the position measuring device does not rise significantly. This quality is important since, as a rule, the evaluation unit downstream from the position measuring device in question is only designed for supplying power to one single scanning unit.
In one aspect, the invention is a method for transmitting data among memory units of at least one position measuring device, said data being stored in a first one of the memory units, comprising connecting the memory units with a data transmission line, transmitting the data from the first memory unit into a second memory unit, such that after the data are transmitted, the data of the first memory unit are at least partially contained in the second memory unit.
In another aspect, the invention is a system for transmitting data among memory units of at least one position measuring devices, the data being stored in the memory units. The system comprises a data transmission line adapted to connect the memory units to transmit data from a first memory unit into a second memory unit, and means for controlling transmission of the data such that once the data are transmitted, the data of the first memory unit are at least partially stored in the second memory unit.
The present invention is not limited to devices operating on one specific scanning principle for producing positionally dependent signals in the particular position measuring device. Rather, it can be used in optical, magnetic, capacitive, as well as in inductive position measuring devices. In addition, the present invention can also be used in conjunction with position measuring devices where the memory units are disposed in the scanning unit.